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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network231.136.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
231.136.0.0
Broadcast address
231.143.255.255
First usable
231.136.0.1
Last usable
231.143.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E7880000 · Integer 3884449792 to 3884974079
Reverse DNS zones
136.231.in-addr.arpa
137.231.in-addr.arpa
138.231.in-addr.arpa
139.231.in-addr.arpa
140.231.in-addr.arpa
141.231.in-addr.arpa
142.231.in-addr.arpa
143.231.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100111.10001000.00000000.00000000231.136.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11100111.10001000.00000000.00000000231.136.0.0
Broadcast11100111.10001111.11111111.11111111231.143.255.255
Split into smaller subnets/20
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

231.136.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1231.136.0.0/20231.136.0.1 to 231.136.15.254231.136.15.2554,094
2231.136.16.0/20231.136.16.1 to 231.136.31.254231.136.31.2554,094
3231.136.32.0/20231.136.32.1 to 231.136.47.254231.136.47.2554,094
4231.136.48.0/20231.136.48.1 to 231.136.63.254231.136.63.2554,094
5231.136.64.0/20231.136.64.1 to 231.136.79.254231.136.79.2554,094
6231.136.80.0/20231.136.80.1 to 231.136.95.254231.136.95.2554,094
7231.136.96.0/20231.136.96.1 to 231.136.111.254231.136.111.2554,094
8231.136.112.0/20231.136.112.1 to 231.136.127.254231.136.127.2554,094
9231.136.128.0/20231.136.128.1 to 231.136.143.254231.136.143.2554,094
10231.136.144.0/20231.136.144.1 to 231.136.159.254231.136.159.2554,094
11231.136.160.0/20231.136.160.1 to 231.136.175.254231.136.175.2554,094
12231.136.176.0/20231.136.176.1 to 231.136.191.254231.136.191.2554,094
13231.136.192.0/20231.136.192.1 to 231.136.207.254231.136.207.2554,094
14231.136.208.0/20231.136.208.1 to 231.136.223.254231.136.223.2554,094
15231.136.224.0/20231.136.224.1 to 231.136.239.254231.136.239.2554,094
16231.136.240.0/20231.136.240.1 to 231.136.255.254231.136.255.2554,094
17231.137.0.0/20231.137.0.1 to 231.137.15.254231.137.15.2554,094
18231.137.16.0/20231.137.16.1 to 231.137.31.254231.137.31.2554,094
19231.137.32.0/20231.137.32.1 to 231.137.47.254231.137.47.2554,094
20231.137.48.0/20231.137.48.1 to 231.137.63.254231.137.63.2554,094
21231.137.64.0/20231.137.64.1 to 231.137.79.254231.137.79.2554,094
22231.137.80.0/20231.137.80.1 to 231.137.95.254231.137.95.2554,094
23231.137.96.0/20231.137.96.1 to 231.137.111.254231.137.111.2554,094
24231.137.112.0/20231.137.112.1 to 231.137.127.254231.137.127.2554,094
25231.137.128.0/20231.137.128.1 to 231.137.143.254231.137.143.2554,094
26231.137.144.0/20231.137.144.1 to 231.137.159.254231.137.159.2554,094
27231.137.160.0/20231.137.160.1 to 231.137.175.254231.137.175.2554,094
28231.137.176.0/20231.137.176.1 to 231.137.191.254231.137.191.2554,094
29231.137.192.0/20231.137.192.1 to 231.137.207.254231.137.207.2554,094
30231.137.208.0/20231.137.208.1 to 231.137.223.254231.137.223.2554,094
31231.137.224.0/20231.137.224.1 to 231.137.239.254231.137.239.2554,094
32231.137.240.0/20231.137.240.1 to 231.137.255.254231.137.255.2554,094
33231.138.0.0/20231.138.0.1 to 231.138.15.254231.138.15.2554,094
34231.138.16.0/20231.138.16.1 to 231.138.31.254231.138.31.2554,094
35231.138.32.0/20231.138.32.1 to 231.138.47.254231.138.47.2554,094
36231.138.48.0/20231.138.48.1 to 231.138.63.254231.138.63.2554,094
37231.138.64.0/20231.138.64.1 to 231.138.79.254231.138.79.2554,094
38231.138.80.0/20231.138.80.1 to 231.138.95.254231.138.95.2554,094
39231.138.96.0/20231.138.96.1 to 231.138.111.254231.138.111.2554,094
40231.138.112.0/20231.138.112.1 to 231.138.127.254231.138.127.2554,094
41231.138.128.0/20231.138.128.1 to 231.138.143.254231.138.143.2554,094
42231.138.144.0/20231.138.144.1 to 231.138.159.254231.138.159.2554,094
43231.138.160.0/20231.138.160.1 to 231.138.175.254231.138.175.2554,094
44231.138.176.0/20231.138.176.1 to 231.138.191.254231.138.191.2554,094
45231.138.192.0/20231.138.192.1 to 231.138.207.254231.138.207.2554,094
46231.138.208.0/20231.138.208.1 to 231.138.223.254231.138.223.2554,094
47231.138.224.0/20231.138.224.1 to 231.138.239.254231.138.239.2554,094
48231.138.240.0/20231.138.240.1 to 231.138.255.254231.138.255.2554,094
49231.139.0.0/20231.139.0.1 to 231.139.15.254231.139.15.2554,094
50231.139.16.0/20231.139.16.1 to 231.139.31.254231.139.31.2554,094
51231.139.32.0/20231.139.32.1 to 231.139.47.254231.139.47.2554,094
52231.139.48.0/20231.139.48.1 to 231.139.63.254231.139.63.2554,094
53231.139.64.0/20231.139.64.1 to 231.139.79.254231.139.79.2554,094
54231.139.80.0/20231.139.80.1 to 231.139.95.254231.139.95.2554,094
55231.139.96.0/20231.139.96.1 to 231.139.111.254231.139.111.2554,094
56231.139.112.0/20231.139.112.1 to 231.139.127.254231.139.127.2554,094
57231.139.128.0/20231.139.128.1 to 231.139.143.254231.139.143.2554,094
58231.139.144.0/20231.139.144.1 to 231.139.159.254231.139.159.2554,094
59231.139.160.0/20231.139.160.1 to 231.139.175.254231.139.175.2554,094
60231.139.176.0/20231.139.176.1 to 231.139.191.254231.139.191.2554,094
61231.139.192.0/20231.139.192.1 to 231.139.207.254231.139.207.2554,094
62231.139.208.0/20231.139.208.1 to 231.139.223.254231.139.223.2554,094
63231.139.224.0/20231.139.224.1 to 231.139.239.254231.139.239.2554,094
64231.139.240.0/20231.139.240.1 to 231.139.255.254231.139.255.2554,094
65231.140.0.0/20231.140.0.1 to 231.140.15.254231.140.15.2554,094
66231.140.16.0/20231.140.16.1 to 231.140.31.254231.140.31.2554,094
67231.140.32.0/20231.140.32.1 to 231.140.47.254231.140.47.2554,094
68231.140.48.0/20231.140.48.1 to 231.140.63.254231.140.63.2554,094
69231.140.64.0/20231.140.64.1 to 231.140.79.254231.140.79.2554,094
70231.140.80.0/20231.140.80.1 to 231.140.95.254231.140.95.2554,094
71231.140.96.0/20231.140.96.1 to 231.140.111.254231.140.111.2554,094
72231.140.112.0/20231.140.112.1 to 231.140.127.254231.140.127.2554,094
73231.140.128.0/20231.140.128.1 to 231.140.143.254231.140.143.2554,094
74231.140.144.0/20231.140.144.1 to 231.140.159.254231.140.159.2554,094
75231.140.160.0/20231.140.160.1 to 231.140.175.254231.140.175.2554,094
76231.140.176.0/20231.140.176.1 to 231.140.191.254231.140.191.2554,094
77231.140.192.0/20231.140.192.1 to 231.140.207.254231.140.207.2554,094
78231.140.208.0/20231.140.208.1 to 231.140.223.254231.140.223.2554,094
79231.140.224.0/20231.140.224.1 to 231.140.239.254231.140.239.2554,094
80231.140.240.0/20231.140.240.1 to 231.140.255.254231.140.255.2554,094
81231.141.0.0/20231.141.0.1 to 231.141.15.254231.141.15.2554,094
82231.141.16.0/20231.141.16.1 to 231.141.31.254231.141.31.2554,094
83231.141.32.0/20231.141.32.1 to 231.141.47.254231.141.47.2554,094
84231.141.48.0/20231.141.48.1 to 231.141.63.254231.141.63.2554,094
85231.141.64.0/20231.141.64.1 to 231.141.79.254231.141.79.2554,094
86231.141.80.0/20231.141.80.1 to 231.141.95.254231.141.95.2554,094
87231.141.96.0/20231.141.96.1 to 231.141.111.254231.141.111.2554,094
88231.141.112.0/20231.141.112.1 to 231.141.127.254231.141.127.2554,094
89231.141.128.0/20231.141.128.1 to 231.141.143.254231.141.143.2554,094
90231.141.144.0/20231.141.144.1 to 231.141.159.254231.141.159.2554,094
91231.141.160.0/20231.141.160.1 to 231.141.175.254231.141.175.2554,094
92231.141.176.0/20231.141.176.1 to 231.141.191.254231.141.191.2554,094
93231.141.192.0/20231.141.192.1 to 231.141.207.254231.141.207.2554,094
94231.141.208.0/20231.141.208.1 to 231.141.223.254231.141.223.2554,094
95231.141.224.0/20231.141.224.1 to 231.141.239.254231.141.239.2554,094
96231.141.240.0/20231.141.240.1 to 231.141.255.254231.141.255.2554,094
97231.142.0.0/20231.142.0.1 to 231.142.15.254231.142.15.2554,094
98231.142.16.0/20231.142.16.1 to 231.142.31.254231.142.31.2554,094
99231.142.32.0/20231.142.32.1 to 231.142.47.254231.142.47.2554,094
100231.142.48.0/20231.142.48.1 to 231.142.63.254231.142.63.2554,094
101231.142.64.0/20231.142.64.1 to 231.142.79.254231.142.79.2554,094
102231.142.80.0/20231.142.80.1 to 231.142.95.254231.142.95.2554,094
103231.142.96.0/20231.142.96.1 to 231.142.111.254231.142.111.2554,094
104231.142.112.0/20231.142.112.1 to 231.142.127.254231.142.127.2554,094
105231.142.128.0/20231.142.128.1 to 231.142.143.254231.142.143.2554,094
106231.142.144.0/20231.142.144.1 to 231.142.159.254231.142.159.2554,094
107231.142.160.0/20231.142.160.1 to 231.142.175.254231.142.175.2554,094
108231.142.176.0/20231.142.176.1 to 231.142.191.254231.142.191.2554,094
109231.142.192.0/20231.142.192.1 to 231.142.207.254231.142.207.2554,094
110231.142.208.0/20231.142.208.1 to 231.142.223.254231.142.223.2554,094
111231.142.224.0/20231.142.224.1 to 231.142.239.254231.142.239.2554,094
112231.142.240.0/20231.142.240.1 to 231.142.255.254231.142.255.2554,094
113231.143.0.0/20231.143.0.1 to 231.143.15.254231.143.15.2554,094
114231.143.16.0/20231.143.16.1 to 231.143.31.254231.143.31.2554,094
115231.143.32.0/20231.143.32.1 to 231.143.47.254231.143.47.2554,094
116231.143.48.0/20231.143.48.1 to 231.143.63.254231.143.63.2554,094
117231.143.64.0/20231.143.64.1 to 231.143.79.254231.143.79.2554,094
118231.143.80.0/20231.143.80.1 to 231.143.95.254231.143.95.2554,094
119231.143.96.0/20231.143.96.1 to 231.143.111.254231.143.111.2554,094
120231.143.112.0/20231.143.112.1 to 231.143.127.254231.143.127.2554,094
121231.143.128.0/20231.143.128.1 to 231.143.143.254231.143.143.2554,094
122231.143.144.0/20231.143.144.1 to 231.143.159.254231.143.159.2554,094
123231.143.160.0/20231.143.160.1 to 231.143.175.254231.143.175.2554,094
124231.143.176.0/20231.143.176.1 to 231.143.191.254231.143.191.2554,094
125231.143.192.0/20231.143.192.1 to 231.143.207.254231.143.207.2554,094
126231.143.208.0/20231.143.208.1 to 231.143.223.254231.143.223.2554,094
127231.143.224.0/20231.143.224.1 to 231.143.239.254231.143.239.2554,094
128231.143.240.0/20231.143.240.1 to 231.143.255.254231.143.255.2554,094

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.